In a display device, many media applications involve the digital image scaling technology. Currently, most display terminals have wide screens such as 16:9 screens. The common resolution of mobile communication terminals is Wide Quarter Video Graphics Array (WQVGA), which represents a screen resolution of 480×272 (aspect radio being 16:9) or 400×240 (aspect ratio being 5:3); or Wide Video Graphics Array (WVGA), which provides a resolution of 800×480 pixels. However, most video sources provide the traditional 4:3 aspect ratio. Consequently, when a user watches videos on the wide screen of a terminal, the scales of the video sources are different from the scale of the display screen, and the video sources need to be scaled up or down so that the video sources are adapted for the size of the display screen.
In the process of implementing the present disclosure, the inventor finds at least the following problems in the prior art: Currently, display devices use traditional scaling methods to implement such functions. For example, in an equal-ratio scaling solution in the prior art, the video sources are adapted to the target video size (screen size) simply, which distorts the scene features in the video, especially scenes of persons, and deteriorates the display effect and user experience. In a fixed segmental scaling solution in the prior art, some of the drawbacks in the foregoing solution are overcome, but the segments are fixed, namely, a small scale coefficient is applied to the middle area, but a great scale coefficient is applied to side areas of an image. If a person is not in the middle area, but moves between different areas of the video, the video is distorted drastically, which deteriorates the user experience. In another scaling solution in the prior art, images are defined as a concept of energy. Image “seams” are inserted or deleted repeatedly for the image content in a certain direction in an attempt to change the image scale, and an insertion or deletion mode that minimizes change of the image energy is selected. To put it simply, this scaling solution makes modification in the areas that provide few details of the image, so as to change the image scale. Such a technique exists as software in desktop computers currently, and is rather popular. However, the scaling solution conflicts with the concept of streamline design. The technique makes repeated attempts to find the optimum value, which involves too many uncertainties. The implementation of such a technique is difficult, and it is almost impossible to implement the technique in the hardware of a cost-efficient device with low power consumption in the iteration process. In conclusion, the prior art leads to distortion of the scaled image, brings adverse effects such as fattened and shortened persons in the image, and deteriorates the user experience.